Thymol blue

Thymol blue

Names
IUPAC name 4-[9-(4-hydroxy-2-methyl-5-propan- 2-yl-phenyl)-7,7-dioxo-8-oxa- 7λ6-thiabicyclo[4.3.0]nona-1,3,5-trien-9-yl]- 5-methyl-2-propan-2-yl-phenol
Other names α-hydroxy-α,α-bis(5-hydroxycarvacryl)- o-toluenesulfonic acid γ-sultone; thymolsulfonephthalein
Identifiers
CAS Number	76-61-9 N
3D model (Jmol)	Interactive image
ChemSpider	59008 Y
ECHA InfoCard	100.000.886
PubChem	65565
InChI InChI=1S/C27H30O5S/c1-15(2)19-13-22(17(5)11-24(19)28)27(21-9-7-8-10-26(21)33(30,31)32-27)23-14-20(16(3)4)25(29)12-18(23)6/h7-16,28-29H,1-6H3 Y Key: PRZSXZWFJHEZBJ-UHFFFAOYSA-N Y InChI=1/C27H30O5S/c1-15(2)19-13-22(17(5)11-24(19)28)27(21-9-7-8-10-26(21)33(30,31)32-27)23-14-20(16(3)4)25(29)12-18(23)6/h7-16,28-29H,1-6H3 Key: PRZSXZWFJHEZBJ-UHFFFAOYAE
SMILES O=S2(=O)OC(c1ccccc12)(c3cc(c(O)cc3C)C(C)C)c4cc(c(O)cc4C)C(C)C
Properties
Chemical formula	C27H30O5S
Molar mass	466.59 g·mol−1
Appearance	Brownish-green crystal powder
Melting point	221–224 °C (430–435 °F; 494–497 K) decomposes
Solubility in water	Insoluble
UV-vis (λmax)	594 nm (1st) 376 nm (2nd)
Hazards
Main hazards	Harmful
EU classification (DSD)	Xn N
NFPA 704	1 1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YN ?)
Infobox references

Thymol blue (thymolsulphonephthalein) is a brownish-green or reddish-brown crystalline powder that is used as a pH indicator. It is insoluble in water but soluble in alcohol and dilute alkali solutions.

It transitions from red to yellow at pH 1.2–2.8 and from yellow to blue at pH 8.0–9.6. It is usually a component of Universal indicator.

Thymol blue has different structures at different pH.

It may cause irritation. Its toxicological properties have not been fully investigated.